Safety valve



H. CAVE SAFETY VALVE:

June 7, 1938.

Filed Oct. 24. 1955 Patented June 7, 1938 UNITED STATES PATENT OFFICE 6 Claims.

My invention relates to the class of devices which are employed for automatically relieving excessive pressures, as of steam, gas, or other fluids, and an' object of my invention, among others, is to provide a safety valve with means whereby its action under a predetermined pressure will be ensured; and a further object of the invention is to provide a safety valve with means for automatically moving the valve on its seat under predetermined conditions or at certain predetermined periods to prevent its sticking.

One form of a safety valve embodying my invention and in the construction and use of which the objects herein set out, as well as others, may be attained, is illustrated in the accompanying. drawing in which- Figure 1 is a side view of the top portion of a hot water tank showing my improved valve attached thereto.

Figure 2 is a similar view looking at the device from a point located at right angles to the point of view of Fig. 1.

Figure 3 is atop view.

Figure 4 is a view on enlarged scale in vertical section through my improved valve.

Figure 5 is a view in section on a plane denoted by the dotted line 5-5 of Fig. 4.

Figure 6 is a view in horizontal section through the structure on a plane denoted by the dotted line 66 of Fig. 4. 4

Figure 7 is a detail view showing a modification of my improved valve.

In the use of safety valves for relieving excessive pressures such valves are frequently installed under conditions which cause them to unduly stick to their seats to such an extent that undue pressure will be created to a dangerous degree. While means is often provided for manually opening the valve whereby the valve may be moved at intervals to avoid such dangerous conditions, its reliance upon the human element makes such operation very uncertain. The conditions hereinabove related are prevalent in connection with hot water tanks or boilers employed for household purposes although it will be evident that my invention will be adapted to any structures in which pressures are created to an excessive extent.

One of many different forms in which my invention may be embodied is illustrated in the accompanying drawing in which the numeral 8 denotes a hot water tank or boiler of the kind usually employed for heating water for domestic purposes, 9 a tube extending out from the top of the boiler, ill the case of my improved valve and H a pipe extending out from the case for outflow of fluid therefrom.

A relief valve I2 is engaged with a valve seat l3 within the case to control outflow through the tube 9. A valve stem It extends outwardly: through a cap l5 secured as by means of screw threads to the top of the case. A spring I6 is mounted on top of the cap l5 and engages with acollar on the stem I4 to hold the valve pressed against its seat. A lever l1 pivotally mounted on an arm l8 extending upwardly from the cap I5 and with one end engaged with the collar on the valve stem may be employed for manual operationof the valve to open it when desired.

A lug l9 extendsputwardly from one side of the valve, as shown in Fig. 6, and a thermostatic bar 20 is pivotally attached at one end to said lug and at its opposite end to a stud 2| projecting upwardly from the bottom of the case Ill. The bar 20 is of such construction, well known to those skilled in the art, that it will lengthen and shorten under changes in temperatures and the action of the device will therefore .be readily seen. As the bar lengthens or shortens under changes in conditions of temperature the valve will be moved on its seat while being spring pressed into contact with its seat to prevent release of a predetermined amount of pressure withinthe boiler. In the structure herein, this shifting is in the character of a rotating or lateral movement permitted by a rotating action of the stem M in the cap l5. When such amount of pressure is exceeded the spring l6 will permit the valve to open, and this opening under such predetermined amount of pressure will be ensured for the reason that the valve is intermittently moved on its seat and sticking is therefore avoided.

In that form of the device hereinbefore described the thermostatic bar depends mainly for its operation upon temperatureconditions with- I in the boiler. In that form of the device shown in Fig. 7 the operation of the device in addition to changes of temperature within the boiler also is influenced by temperature changes in atmospheric conditions without the boiler so that in cases where the boiler is not in use for some periods the regular atmospheric conditions will operate to move the valve on its seat. In this form of the device the thermostatic bar 22 extends from the valve within the case outwardly through a. diaphragm 23 secured within an opening on one side of the case as by means of a nut screwed on to a hub on said case. The bar is secured to the diaphragm-by a nut 24 and is supported from sliding movement at its outer end in an arm 25 projecting from the side of the case 26.

I have in mind several different arrangements for intermittently moving the valve to prevent its sticking and these may embody different means for effecting this result by means of changes in temperature. It will also be obvious that agents other than temperature changes may be utilized for intermittently moving the valve on its seat without departing from the spirit and intent of my invention.

While mention has been made herein of the valve as sticking to its seat it is also noted that the same condition might be created as to the stem or other support for the valve, which condition would be also relieved by my improved device. be applied to structures other than safety valves.

In accordance with the provisions of the patent statutes I have described the principles of operation of my invention, together with the device which I now consider to represent the best embodiment thereof; but I desire to have it understood that the device. shown is only illustrative and that the invention may be carried out by other means and applied to uses other than those above set out.

It will be understood that the term boiler as used herein is intended to'include various receptacles or containers in which excessive pressures of air, gas, steam, and other fluids are liable to exist.

I claim:

1. An attachment for relief of excessive pressure in a boiler comprising a valve housing having an inlet and an outlet and a valve seat therebetween, a valve disk mounted for opening and closing movements relatively to said seat, means for .urging said disk toward the seat, and means responsive to temperature changes and attached at one point to said disk and rigidly supported at anotherpoint relatively to'the housing whereby changes in temperature will cause said last named means solely to shift the valve laterally on its seat to prevent sticking.

2. An attachment for relief of excessive pressure in a boiler comprising a valve housing having an inlet and an outlet and a valve seat'therebetween, a valve disk mounted for axial moveother end relatively to the housing whereby changes in temperature will cause said last named It will be obvious also that the idea may means to shift the valve laterally on its seat to prevent sticking.

3. An attachment for relief of excessive pressure in a boiler comprising a valve housing having an inlet and an outlet and a valve seat therebetween, a valve disk mounted for axial movement to and from said seat, a valve stem projecting from said valve outwardly through said housing, means supported by said housing and thrusting against said stem to force said valve towards its seat, and means responsive to temperature changes and fixed at one end to said disk and rigidly supported at the other end relatively to the housing whereby changes in temperature will cause said last named means to shift the valve laterally on its seat to prevent sticking.

4. An attachment for relief of excessive pressure in a boiler comprising a valve housing having an inlet and an outlet and a valve seat therebetween and also having an enlarged opening through its wall, an arm projecting from said housing opposite said opening, a valve disk mounted for opening and closing movements relatively to said seat, pressure means for urging said disk toward the seat, and shifting means responsive to temperature changes and attached at one end to said disk and extending through said opening and rigidly supported at the other end by said arm whereby changes in'temperature ing an inlet and an outlet and a valve seat therebetween, a valve disk mounted for opening and closing movements relatively to said seat, pressure means for urging said disk toward its seat, and means for solely sliding the valve on its seat independently of any opening movement thereof, said last named means being responsive to temperature changes whereby the valve is periodically shifted on its seat without opening movement thereof.

6. An attachment for relief of excessive pressure in a boiler comprising a valve housing having an inlet and an outlet and a valve seat therebetween, a valve disk mounted for opening and closing movements axially of said seat, means for urging said valvedisk toward the seat and a thermostatic element directly attached to said valve disk and housing whereby changes in temperaturewill cause said thermostatic element to shift the valve disk laterally on its seat to prevent sticking.

HENRY CAVE. 

